Reactions of 3-Acylchromones with Heterocyclic Ketene Aminals: One-Pot Synthesis and Phosphatase Inhibitory Activity of Fused Pyridine Derivatives

Domino reactions of 3-acylchromones, namely 3-methoxalyl-, 3-aroyl- and 3-cinnamoylchromones, with heterocyclic ketene aminals (HKAs) proceed by attack of the nucleophile on the C-2 atom of the chromone moiety, pyrone ring-opening and subsequent formal [3+3] cyclocondensation with formation of functionalized tetracyclic fused chromeno[2,3-b]pyridines or 2H,3H-imidazo[1,2-a]pyridines. The product distribution depends on the type of acyl group located at the 3-position of the chromone and on the size of the heterocyclic moiety of the HKAs. The products show a considerable activity as selective phosphatase inhibitors.